Deploying Rails on Google&#39;s App Engine has become a lot easier than it used to be. There are a couple of caveats you should be aware of:

 - App Engine only supports the Python and Java environments so for Rails you will be deploying on [JRuby][1]
 - App Engine&#39;s datastore is based on BigTable so you won&#39;t be able to use ActiveRecord on a relational database (if you want your datastore hosted in AppEngine). But as @Geoff Lanotte as pointed out there is a Datamapper adapter you can use
 - Pre-deployment testing is done within Google&#39;s sandbox tools as opposed to things like `script/server`

Some other resources you might consider:

[http://code.google.com/p/appengine-jruby/][2]

[http://rails-primer.appspot.com/][3]

[http://gist.github.com/335023][4]


  [1]: http://jruby.org/
  [2]: http://code.google.com/p/appengine-jruby/
  [3]: http://rails-primer.appspot.com/
  [4]: http://gist.github.com/335023

You can deploy Ruby on Rails on **Google Compute Engine** if it works for you. Compute Engine is Iaas (Infrastructure as a Service) and it is used by Google App Engine, which is PaaS (Platform as a Service).
Compute Engine is one abstraction layer lower (you can access OS resources, like: file system, network etc.).

**Detailed instructions:**
http://startup-with-gae.blogspot.com/2015/08/how-to-deploy-ruby-on-rails-application.html

I&#39;m experimenting with some styles on `&lt;textarea&gt;`s and I tried doing some stuff with `::before` and `::after` selectors and I couldn&#39;t to anything to get them to work. So the question is: is this possible? I know the CSS surrounding forms is arcane beyond mention but it seems like this should work.

Can a ::before selector be used with a &lt;textarea&gt;?

I have an Excel worksheet I want to read into a datatable - all is well except for one particular column in my Excel sheet. The column, &#39;ProductID&#39;, is a mix of values like `##########` and `n#########`.

I tried to [let OleDB handle everything by itself automatically][1] by reading it into a dataset/datatable, but any values in &#39;ProductID&#39; like `n######` are missing, ignored, and left blank.  I tried manually creating my DataTable by looping through each row with a datareader, but with the exact same results.

Here&#39;s the code :

&lt;!-- language: lang-cs --&gt;

    // add the column names manually to the datatable as column_1, column_2, ...
    for (colnum = 0; colnum &lt; num_columns; colnum ++){
      ds.Tables[&quot;products&quot;].Columns.Add(&quot;column_&quot; +colnum , System.Type.GetType(&quot;System.String&quot;)); 
    }
    while(myDataReader.Read()){
      // loop through each excel row adding a new respective datarow to my datatable 
      DataRow a_row = ds.Tables[&quot;products&quot;].NewRow();
      for (col = 0; col &lt; num_columns; col ++){
        try {  a_row[col] = rdr.GetString(col);  }
        catch {  a_row[col] = rdr.GetValue(col).ToString(); }
      }
      ds.Tables[&quot;products&quot;].Rows.Add(a_row);
    }

I don&#39;t understand why it won&#39;t let me read in values like `n######`. How can I do this? 

  [1]: http://support.microsoft.com/kb/306572

OleDB &amp; mixed Excel datatypes : missing data

Can anyone give me some pointers on how I could deploy my rails app to GAE? I&#39;ve been reading about it, but it seems to be a fairly complicated task.

I tried with the `google-appengine` gem, but its not a piece of cake either.

Has there been any progress with the `DataMapper` adapter or will I need to make changes to my models?

I was hoping to see a full-detail tutorial about it, but those that I found were somewhat out-of-date.

Ruby on Rails app on Google App Engine

Can anyone give me some pointers on how I could deploy my rails app to GAE? I've been reading about it, but it seems to be a fairly complicated task.
I tried with the <code>google-appengine</code> gem, but its not a piece of cake either.
Has there been any progress with the <code>DataMapper</code> adapter or will I need to make changes to my models?
I was hoping to see a full-detail tutorial about it, but those that I found were somewhat out-of-date.

I was wondering if there&#39;s a way in Rails to calculate time stamp like - half a minute ago, 2 minute ago, 1 day ago etc. Something like twitter real time date stamp.

I want to know if Ruby/Rails has a built-in function for such date-time conversion?

&quot;Ago&quot; date/time functions in Ruby/Rails

I&#39;m creating a new engine for a rails 3 application. As you can guess, this engine is in the lib directory of my application.

However, i have some problems developing it. Indeed, I need to restart my server each time I change something in the engine.

Is there a way to avoid this ?

Can I force rails to completely reload the lib directory or a specific file and his requirements for each request ?

Thanks for your help :)

Ruby on Rails 3 - Reload lib directory for each request

I need an SQL statement that check if one condition is satisfied:

    SELECT * FROM my_table WHERE my_table.x=1 OR my_table.y=1

I want to do this the &#39;Rails 3&#39; way. I was looking for something like:

    Account.where(:id =&gt; 1).or.where(:id =&gt; 2)

I know that I can always fallback to sql or a conditions string. However, in my experience this often leads to chaos when combining scopes. What is the best way to do this?

Another related question, is how can describe relationship that depends on an OR condition. The only way I found:

    has_many :my_thing, :class_name =&gt; &quot;MyTable&quot;,  :finder_sql =&gt; &#39;SELECT my_tables.* &#39; + &#39;FROM my_tables &#39; +
    &#39;WHERE my_tables.payer_id = #{id} OR my_tables.payee_id = #{id}&#39;

However, these again breaks when used in combinations. IS there a better way to specify this?

Ruby on Rails 3 howto make &#39;OR&#39; condition

You can get the `current_user`&#39;s permissions from a view or controller using `can?` in this fashion:

      &lt;% if can? :update, @article %&gt;
        &lt;%= link_to &quot;Edit&quot;, edit_article_path(@article) %&gt;
      &lt;% end %&gt;

How can I access this functionality from a model using this syntax:

    user.can?(:update, @article)

Access CanCan&#39;s `can?` method from a model

I have model Person that has many Images, where images has a Paperclip attachment field called data, an abbreviated version displayed below:

    class Person
      has_many :images
      ...
    end

    class Image
      has_attached_file :data
      belongs_to :person
      ...
    end


Person is required to have at least one Image attached to it.

When using FactoryGirl, I have code akin to the following:

    Factory.define :image do |a|
      a.data { File.new(File.join(Rails.root, &#39;features&#39;, &#39;support&#39;, &#39;file.png&#39;)) }
      a.association :person
    end

    Factory.define :person do |p|
      p.first_name &#39;Keyzer&#39;
      p.last_name &#39;Soze&#39;
      p.after_create do |person|
        person.assets = [Factory.build(:image, :person =&gt; person)]
      end
      # p.images {|images| [images.association(:image)]}
    end

(N.B. I have also tried the code commented out above was also tried)
Most of the time when I run cucumber features, I get an error akin to the following:
&gt; No such file or directory - /tmp/stream,9887,0.png (Errno::ENOENT)
&gt;
&gt; ...

Sometimes the tests run successfully.

Can anyone tell me what the problem is I am having here or how they use FactoryGirl and Paperclip together to achieve something like what I am trying to achieve?

I am using Rails 3.

How Do I Use Factory Girl To Generate A Paperclip Attachment?

I just had a quick question regarding loops in Ruby. Is there a difference between these two ways of iterating through a collection?

    # way 1
    @collection.each do |item|
      # do whatever
    end

    # way 2
    for item in @collection
      # do whatever
    end

Just wondering if these are exactly the same or if maybe there&#39;s a subtle difference (possibly when `@collection` is nil).

&quot;for&quot; vs &quot;each&quot; in Ruby

I know in Ruby that I can use `respond_to?` to check if an object has a certain method.

But, given the class, how can I check if the instance has a certain method?

i.e, something like

    Foo.new.respond_to?(:bar)

But I feel like there&#39;s gotta be a better way than instantiating a new instance.


Given a class, see if instance has method (Ruby)

Delayed::Job&#39;s auto-retry feature is great, but there&#39;s a job that I want to manually retry now. Is there a method I can call on the job itself like...

    Delayed::Job.all[0].perform

or run, or something. I tried a few things, and combed the documentation, but couldn&#39;t figure out how to execute a manual retry of a job.





Manually Retry Job in Delayed_job

Having properly configured a *Development* server and a *Production* server, I would like to set up a *Staging* environment on Google App Engine useful to test new developed versions live before deploying them to production.

I know two different approaches:

**A.** The first option is by modifying the [app.yaml][1] **version** parameter.

    version: app-staging

What I don&#39;t like of this approach is that Production data is polluted with my staging tests because (correct me if I&#39;m wrong):

 1. Staging version and Production version share the same Datastore 
 2. &lt;strike&gt;Staging version and Production version share the same logs&lt;/strike&gt;

&lt;sub&gt;Regarding the first point, I don&#39;t know if it could be &quot;fixed&quot; using the new [namespaces python API][2].&lt;/sub&gt;


**B.** The second option is by modifying the [app.yaml][3] **application** parameter

    application: foonamestaging

with this approach, I would create a second application totally independent from the Production version.  
The only drawback I see is that I&#39;m forced to configure a second application (administrators set up).  
With a backup\restore tool like [Gaebar][4] this solution works well too.

What kind of approach are you using to set up a staging environment for your web application?  
Also, do you have any automated script to change the yaml before deploying?


  [1]: http://code.google.com/appengine/docs/python/config/appconfig.html
  [2]: http://code.google.com/appengine/docs/python/multitenancy/overview.html
  [3]: http://code.google.com/appengine/docs/python/config/appconfig.html
  [4]: http://aralbalkan.com/1784

How to set up a staging environment on Google App Engine

I&#39;ve got a file in my war/WEB-INF folder of my app engine project. I read in the FAQs that you can read a file from there in a servlet context. I don&#39;t know how to form the path to the resource though:

    /war/WEB-INF/test/foo.txt

How would I construct my path to that resource to use with File(), just as it looks above?

Thanks

File path to resource in our war/WEB-INF folder?

I need to use UTF-8 in my resource properties using Java&#39;s `ResourceBundle`. When I enter the text directly into the properties file, it displays as mojibake.

My app runs on Google App Engine.

Can anyone give me an example? I can&#39;t get this work.

How to use UTF-8 in resource properties with ResourceBundle

What&#39;s the best strategy for managing third-party Python libraries with Google App Engine?

Say I want to use Flask, a webapp framework. [A blog entry](http://www.franciscosouza.com/2010/08/flying-with-flask-on-google-app-engine/) says to do this, which doesn&#39;t seem right:

    $ cd /tmp/
    $ wget http://pypi.python.org/packages/source/F/Flask/Flask-0.6.1.tar.gz
    $ tar zxf Flask-0.6.1.tar.gz
    $ cp -r Flask-0.6.1/flask ~/path/to/project/
    (... repeat for other packages ...)

There must be a better way to manage third-party code, especially if I want to track versions, test upgrades or if two libraries share a subdirectory. I know that Python can import modules from zipfiles and that _pip_ can work with a wonderful REQUIREMENTS file, and I&#39;ve seen that _pip_ has a `zip` command for use with GAE.

(Note: There&#39;s a handful of similar questions — [1], [2], [3], [4], [5] — but they&#39;re case-specific and don&#39;t really answer my question.)

[1]: https://stackoverflow.com/questions/3899706/including-a-third-party-python-package-in-django-on-app-engine
[2]: https://stackoverflow.com/questions/4530183/python-eggs-on-google-app-engine
[3]: https://stackoverflow.com/questions/4090268/google-app-engine-python-virtualenv-and-mimetypes
[4]: https://stackoverflow.com/questions/2139693/unittest-import-error-with-virtualenv-google-app-engine-django
[5]: https://stackoverflow.com/questions/2743806/best-deployment-strategy-for-python-google-app-engine

How do I manage third-party Python libraries with Google App Engine? (virtualenv? pip?)

Since app engine 1.4.2 was released, I am getting warnings like this in my production logs:

&gt; You are using the default Django
&gt; version (0.96). The default Django
&gt; version will change in an App Engine
&gt; release in the near future. Please
&gt; call use_library() to explicitly
&gt; select a Django version. For more
&gt; information see
&gt; http://code.google.com/appengine/docs/python/tools/libraries.html#Django

This occurs on every handler where I use a Django template - via the following:

    from google.appengine.ext.webapp import template

I&#39;d like to upgrade to 1.2, however the following links don&#39;t seem very clear on exactly how to do this (or whether it works at all):

- http://code.google.com/appengine/docs/python/tools/libraries.html#Django
- http://code.google.com/p/googleappengine/issues/detail?id=1758
- http://code.google.com/p/googleappengine/issues/detail?id=4489
- http://www.mediacrafters.org/post/django11-on-appengine

The common thread is to insert this:

    from google.appengine.dist import use_library
    use_library(&#39;django&#39;, &#39;1.2&#39;)

However, in what file(s) should this be inserted:

1. Just in appengine_config.py?
2. In every .py file which does `from google.appengine.ext.webapp import template`?
3. In every .py file in the project?
4. In 1 and (2 or 3) above, and also add `import appengine_config` to those files?
5. In 3 or 4, and also add wrappers around built-in functions like appstats, remote api, datastore admin, etc?
6. Something else?

Thanks.


Content Type	Original Author	Original Content on Stackoverflow
Question	Albus Dumbledore	View Question on Stackoverflow
Solution 1 - Ruby on-Rails	bjg	View Answer on Stackoverflow
Solution 2 - Ruby on-Rails	Maciej	View Answer on Stackoverflow

Ruby on Rails app on Google App Engine

Ruby on-Rails Problem Overview

Ruby on-Rails Solutions

Solution 1 - Ruby on-Rails

Solution 2 - Ruby on-Rails

OleDB & mixed Excel datatypes : missing data

Can a ::before selector be used with a <textarea>?

Attributions